Advanced methane and ammonia recovery system

0001The present application is a Continuation In Part of U.S. patent application Ser. No. 11/754,057 filed May 25, 2007, which application is incorporated in its entirety herein by reference.

BACKGROUND OF THE INVENTION

0002The present invention relates to processing treatment of waste from domestic livestock and poultry operations and in particular to an integrated system for efficiently capturing and processing waste material from domestic livestock and poultry operations including methane gas which has been estimated to makeup about one fifth of recognized green house gas effects.

0003Domestic livestock and poultry operations in the United States produce a substantial portion of the food regularly consumed by the pubic. Unfortunately, these operations also produce significant waste which must be dealt with, and significant odors not appreciated by local residents. Until the present time, no large scale systems have been developed to deal efficiently with these waste products.

0004Further, both sheep and cows are ruminant animals. Ruminant animals include a rumen, a special stomach which allows them to digest plants not normally digestible. Enteric fermentation takes place in the rumen producing methane gas. The methane gas is later released to the atmosphere. Methane gas traps much more heat than carbon dioxide and may linger in the atmosphere over a decade. Scientists have estimated that methane gas is responsible for one fifth of greenhouse warming. Unfortunately, no effective solution has been provided to capture the methane gas released by cows, sheep and other ruminant animals.

BRIEF SUMMARY OF THE INVENTION

0005The present invention addresses the above and other needs by providing an advanced methane and ammonia recovery system which captures gaseous waste produced by domestic livestock to reduce the release of greenhouse gasses into the atmosphere and to generate energy. The system includes a gas capture system residing at a peak of a barn. At large commercial operations, the captured gasses pass through a separator to separate methane from ammonia gas. The ammonia is processed to obtain a fertilizer. The methane is stored in a tank, and drawn from the tank to provide fuel for an electrical generator. At smaller operations, the captured gasses may be stored in a tank for periodic collection by a tanker truck or other transportation, or where economically feasible, piped to a central processing location. The system is designed to substantially reduce the amount of methane gas released into the environment while providing additional income to the domestic livestock operations.

0006In accordance with one aspect of the invention, there is provided a gas recovery system including a barn, a gas capture vessel, an ammonia/methane separator, a membrane unit, and a methane storage tank. The gas capture vessel has a height between approximately 20 feet and approximately 25 feet and a diameter between approximately eight feet and approximately ten feet, and resides at a peak of the barn for collecting gaseous waste. A first methane sensor resides inside the gas capture vessel between approximately two feet and approximately four feet below a top of the gas capture vessel and a second methane sensor resides inside the gas capture vessel vertically between approximately 2.5 feet and approximately four feet above a bottom of the gas capture vessel. A first duct fluidly connects the gas capture vessel to the ammonia/methane separator and a second duct fluidly connects the ammonia/methane separator and the membrane unit. A fan resides in the flow between the ammonia/methane separator and the membrane unit and controlled by the first methane sensor and the second methane sensor. A third duct fluidly connects the membrane unit to the methane storage tank for carrying methane from the membrane unit to the methane storage tank. The membrane unit separates methane gas from other gasses and the methane gas stored in the methane storage tank may be used to power a generator.

0007In accordance with another aspect of the invention, there is provided a gas recovery system including a barn, a gas capture vessel residing at a peak of the upper tent portion for collecting gaseous waste, external beams residing outside the barn and supporting the gas capture vessel independently of the barn, and a gas storage tank. The barn includes a lower post portion comprising vertical posts and open between the posts and an upper tent portion forming an upward concave cavity. A duct is connected to the gas capture vessel for carrying the gaseous waste from the gas capture vessel toward the gas storage tank, a fan moves the gaseous waste from the capture vessel toward the gas storage tank, and a gas sensor is positioned to detect the presence of the gaseous waste in the peak of the tent portion, the capture vessel, or the duct.

0008In accordance with yet another aspect of the invention, there is provided a method for controlling a gas recovery system. The method includes the steps of initially turning to OFF a fan used to draw gaseous waste from a gas capture vessel through the gas recovery system. The system then enters a loop and tests if the fan is ON or OFF. If the fan is ON and if a first gas sensor residing inside the gas capture vessel proximal to a top of the gas capture vessel is sensing the presence of the gaseous waste, the fan remains ON. If the fan is ON and if the first gas sensor is not detecting the presence of the gaseous waste, the fan is turned OFF. If the fan is OFF, it is left OFF if either or both the first gas sensor is not sensing the presence of the gaseous waste and a second gas sensor residing inside the gas capture vessel proximal to a bottom of the gas capture vessel is not sensing the presence of the gaseous waste. If the fan is OFF, it is turned ON if both gas sensors are detecting the presence of the gaseous waste.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

0009The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein:

0010<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram of a methane and ammonia recovery system according to the present invention.

0011<figref idref="DRAWINGS">FIG. 2</figref> depicts a barn with a gas capture vessel residing at a peak, and gas processing equipment.

0012<figref idref="DRAWINGS">FIG. 3</figref> shows a perspective view of the gas capture vessel.

0013<figref idref="DRAWINGS">FIG. 4</figref> shows a side view of the gas capture vessel.

0014<figref idref="DRAWINGS">FIG. 5</figref> is a cross-sectional view of the gas capture vessel taken along line <b>5</b>-<b>5</b> of <figref idref="DRAWINGS">FIG. 4</figref>.

0015<figref idref="DRAWINGS">FIG. 6</figref> shows a cap and body of the gas capture vessel.

0016<figref idref="DRAWINGS">FIG. 7</figref> is a method according to the present invention.

0017<figref idref="DRAWINGS">FIG. 8</figref> depicts a small barn with the gas capture vessel residing at a peak, and gas containment equipment.

0018Corresponding reference characters indicate corresponding components throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

0019The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims.

0020An advanced methane and ammonia recovery system according to the present invention is shown functionally in <figref idref="DRAWINGS">FIG. 1</figref> and geometrically in <figref idref="DRAWINGS">FIG. 2</figref>. Livestock residing in a barn, house, and/or enclosure <b>10</b> produces gaseous waste. The barn <b>10</b> comprises a base (or post) portion <b>10</b><i>a </i>and a tent portion <b>10</b><i>b </i>covered by a covering <b>14</b>. The post portion comprises a multiplicity of vertical posts <b>12</b> supporting the tent portion <b>10</b><i>b</i>. The tent portion <b>10</b><i>b </i>includes an approximately horizontal closed bottom edge <b>11</b> and forms an upward concave cavity <b>13</b> and may be any solid surface which traps waste gas rising from beneath. A gas capture vessel <b>16</b> resides at a peak <b>18</b> of the tent portion <b>10</b><i>b</i>. The gas capture vessel <b>16</b> is preferably centered along the peak <b>18</b> and two collecting ducts <b>19</b> run from the gas capture vessel <b>16</b> in opposite directions above the peak <b>18</b> approximately ⅔ of the distance from the gas capture vessel <b>16</b> to ends of the tent portion <b>10</b><i>b. </i>

0021The gaseous waste is lighter than air and rises into the gas capture vessel <b>16</b> where the gaseous waste is captured. The gaseous waste is collected in the gas capture vessel <b>16</b> and carried by first duct <b>24</b> to an ammonia/methane separator <b>26</b> (for example, an ammonia scrubber). The ammonia/methane separator <b>26</b> separates ammonia from other gasses (primarily methane) in the gaseous waste. The ammonia, which is converted into ammonium sulfate, is carried by ammonia duct <b>42</b> to an ammonium sulfate storage tank <b>44</b> for further drying into fertilizer.

0022The other gasses are carried by second duct <b>28</b> to a membrane unit <b>30</b> where the methane is separated from oxygen and nitrogen. The separation is preferably done by selectively permeable membrane(s). The membrane unit <b>30</b> preferably includes a fan to draw the gaseous waste from the gas capture vessel <b>16</b>, through the ammonia/methane separator <b>26</b>, and to the membrane unit <b>30</b>. Methane captured by the membrane unit <b>26</b> is carried by a third duct <b>32</b> to a methane storage tank <b>34</b>. The methane stored in the methane storage tank <b>34</b> is provided through a fourth duct <b>38</b> to a generator <b>40</b> where the methane is used as fuel to generate electricity.

0023The gas capture vessel <b>16</b> is structurally supported by beams <b>15</b>. Preferably four beams are attached to the gas capture vessel <b>16</b> and reside outside the barn <b>10</b> presenting no load to the barn <b>10</b>. The four beams <b>15</b> are preferably steel “I” beams but may also be trusses.

0024Ventilation assemblies <b>20</b> are attached to the barm <b>10</b> to provide ventilation if measure methane levels exceed a threshold to prevent waste gas from building up in the breathable airspace of the ruminant animals and humans. The ventilation assemblies <b>20</b> preferably reside at opposite ends of the barm <b>10</b> proximal to the height of the peak <b>18</b> and are preferably automatically controlled and comprise vent doors which are opened to vent excess waste gasses. Manual and automatic monitoring and switch unit <b>22</b> reside on one of the posts <b>12</b> allowing an operator to monitor conditions in the barn <b>10</b> and to shut off the components of the advanced methane and ammonia recovery system should unsafe conditions arise. The monitoring may include temperature, levels of one or more gasses in the tent portion <b>10</b><i>b. </i>

0025A perspective view of the gas capture vessel <b>16</b> is shown in <figref idref="DRAWINGS">FIG. 3</figref>, a side view of the gas capture vessel <b>16</b> is shown in <figref idref="DRAWINGS">FIG. 4</figref>, and a cross-sectional view of the gas capture vessel <b>16</b> taken along line <b>5</b>-<b>5</b> of <figref idref="DRAWINGS">FIG. 4</figref> is shown in <figref idref="DRAWINGS">FIG. 5</figref>. The gas capture vessel <b>16</b> comprises a vertical cylindrical body <b>16</b><i>a </i>and a cap <b>16</b><i>b</i>. The cap <b>16</b><i>b </i>may be hemispherical, conical, or other shape with a peak, and is preferably hemispherical. A cylindrical body <b>16</b><i>a </i>of the capture vessel <b>16</b> is preferably made from fiberglass, and a cap <b>16</b><i>b </i>of the capture vessel <b>16</b> is preferably made from steel. The cap <b>16</b><i>b </i>protects the capture vessel <b>16</b> and is grounded to serve as a lighting rod. The first duct <b>24</b> connects to the cap <b>16</b><i>b </i>to draw the gaseous waste from the capture vessel <b>16</b>.

0026A lower band <b>46</b><i>a </i>near the base of the cylindrical body <b>16</b><i>a </i>and a center band <b>46</b><i>b </i>approximately vertically centered on the cylindrical body <b>16</b><i>a </i>along with the cap <b>16</b><i>b </i>are attached to the beams <b>15</b> and to the cylindrical body <b>16</b><i>a </i>to support the capture vessel <b>16</b>, and the beams <b>15</b> also ground the cap <b>16</b><i>b</i>. An air turbulence reduction shield <b>48</b> resides below the capture vessel <b>16</b>. The air turbulence reduction shield <b>48</b> comprises a horizontally residing sheet centered under the peak <b>18</b> and preferably under the ventilation assemblies <b>20</b> and extending approximately the length of the capture vessel. The shield <b>48</b> is preferably square with sides having a length the same as the diameter of the capture vessel <b>16</b>. The air turbulence reduction shield <b>48</b> resides approximately four feet under the peak <b>18</b> and leave horizontal gaps of approximately twelve inches between edges of the air turbulence reduction shield <b>48</b> and the inner surface of the tent portion <b>16</b><i>b</i>. The shield <b>48</b> is preferably made of fiberglass and includes a number of openings <b>48</b><i>a</i>, and is similar to a grating to allow gases to pass through the shield <b>48</b>, but protects ruminant animals and humans below from any explosion.

0027The cylindrical body <b>16</b><i>a </i>has a height H<b>1</b> which is preferably between approximately 20 feet and approximately 25 feet tall and a diameter D<b>1</b> which is preferably between approximately eight feet and approximately ten feet, but may vary outside this range depending on the number of animals in the barn. Gas sensors S<b>1</b><i>a</i>, S<b>1</b><i>b</i>, S<b>2</b><i>a</i>, and S<b>2</b><i>b </i>reside inside the cylindrical body <b>16</b><i>a</i>. The pair of upper gas sensors S<b>1</b><i>a </i>and S<b>1</b><i>b </i>resides proximal to the top of the cylindrical body <b>16</b><i>a </i>and the pair of lower gas sensor S<b>2</b><i>a </i>and S<b>2</b><i>b </i>resides proximal to the base of the cylindrical body <b>16</b><i>a</i>. The gas sensors are preferably methane sensors, but may sense any gas present in the gaseous waste in sufficient quantities to allow reliable sensing of the presence of the gaseous waste in the gas capture vessel <b>16</b>.

0028The cap <b>16</b><i>b </i>is shown separated from the cylindrical body <b>16</b><i>a </i>in <figref idref="DRAWINGS">FIG. 6</figref>.

0029A method for controlling an operation of the gas recovery system is described in <figref idref="DRAWINGS">FIG. 7</figref>. The fan is initially turned to OFF at step <b>100</b> and a control loop is entered. If the fan is ON at step <b>102</b>, and if the first gas sensor S<b>1</b> is detecting (i.e., S<b>1</b>=1) the presence of the gaseous waste, the fan remains ON. If the fan is ON at step <b>102</b>, and if the first gas sensor S<b>1</b> is not detecting (i.e., S<b>1</b>=0) the presence of the gaseous waste at step <b>104</b>, the fan is turned OFF at step <b>105</b>. If the fan is OFF at step <b>102</b>, and if both the first sensor S<b>1</b> is detecting (i.e., S<b>1</b>=1) the presence of the gaseous waste and the second sensor S<b>2</b> is detecting (i.e., S<b>2</b>=1) the presence of the gaseous waste at step <b>106</b>, the fan is turned ON at step <b>108</b>. If the fan is OFF at step <b>102</b>, and if either or both the first sensor S<b>1</b> is not detecting (i.e., S<b>1</b>=0) the presence of the gaseous waste, and the second sensor S<b>2</b> is not detecting (i.e., S<b>2</b>=0) the presence of the gaseous waste at step <b>106</b>, the fan remains OFF. In all cases, the control loop returns to step <b>102</b>.

0030A small barn <b>50</b> with the gas capture vessel <b>16</b> residing at the peak <b>18</b>, and gas containment equipment is shown in <figref idref="DRAWINGS">FIG. 8</figref>. The gas produced in the small barn <b>50</b> may not be sufficient to make the system shown in <figref idref="DRAWINGS">FIGS. 1 and 2</figref> economically feasible. As a result, a small system comprising a fan <b>52</b> connected to the gas capture vessel <b>16</b> by the duct <b>24</b>, and a gas storage tank <b>56</b> connected to the fan <b>52</b> by duct <b>54</b>, is an alternative system. The gas stored in the tank <b>56</b> is periodically collected for processing at a remote location which services small livestock operations in the local area. Further, where a number of small livestock operations are near each other, pipes may connect each small livestock operation to a central processing station comprising the processing elements <b>26</b>-<b>44</b> described in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>. The barn <b>50</b> is otherwise similar to the barn <b>10</b>.

0031While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.